Tum r cells contain abnormal quantities of glyceryl ether phospholipids. Work in this laboratory in the past two years confirms our hypothesis that this abnormality involves the surface membrane. We have shown that these lipids are rapidly labeled in the presence of the precursor, (1-3H) hexadecanol. We have recently obtained preliminary data showing that metastasizing transplantable rat mammary tumors contain more O-alkyl glyceryl ether than their non metastasizing counterparts. Surface membrane O-alkyl glyceryl ether content may be related to total cell O-alkyl glyceryl ether. Because surface membrane abnormalities may be important in the metastasizing behavior of tumors, we propose to continue our current investigation on methods for obtaining solid tumor surface membranes and measuring their glyceryl ether content (as well as whole tumor O-alkyl glyceryl ether content) in metastasizng and non metastasizing tumors. We also propose to investigate the O-alkyl phospholipid content of the outer cell covering, or glycocalyx. We propose to continue ongoing studies on the biosynthesis O-alkyl glyceryl ethers in Ehrlich ascites tumor cells. In the past two years we have obtained data which have led us to propose a mechanism for ether bond formation. This information could be important in understanding the cause of the ether lipid abnormality in neoplasms. Acyl DHAP forms an enediol plus a proton. The endediol then breaks down to DHAP or couples with hexadecanol to form O-alkyl DHAP. In this reaction there is no change in configuration of the hydrogens of carbon one of the DHAP of O-alkyl DHAP. The previously shown hydrogen loss does not require hexadecanol, a finding favoring the concept of an enediol intermediate. Our immediate specific aims are to isolate the enzyme involved in dehydrogenation of acyl DHAP and to study the stereochemistry of the hydrogens of carbon one of the DHAP released.